MAIN WEATHER AND CLIMATE TRAITS IN THE NORTHEN HEMISPHERE AS OF APRIL 2019

Air Temperature

Abnormally warm weather that reigned in Russia for most of March smoothly migrated to April. In the first decade, the temperature was above normal across the whole country, the anomalies increasing northwards and reaching +6…14° in the arctic region of Siberia and of the Far East. The record-breaking temperature maxima were repeatedly recorded in Yakutia, in the Magadan Region, Chukotka Autonomous district, Kamchatka and northern Krasnoyarsk Territories, Altai Mountains, and in the Kaliningrad Region in the west of the country.In the second decade, the weather abruptly changed its temper. Significant excess heat survived solely in the North-East Russia, in parts of the Primorye Territory where new records of warmth were set, and in the Russian North. In the rest of Russia, warmth was ousted by arctic cold whose intrusion was especially remarkable in Western Siberia where the anomalies of decade-averaged temperatures became negative (-1…-3°). And the latter was also true for the European territory (viz., in the South and Volga Federal districts) where the decade-averaged air temperature was, if slightly, below normal as well. There, the weather on certain days was nevertheless warm, occasionally reaching the record-breaking temperature maxima in the Tambov, Penza, Saratov and Sverdlovsk Regions.In the very beginning of the third decade, it became colder in the Volga Region, in the Urals and in Western Siberia: in essence, winter returned there. New temperature minima were recorded in the Sverdlovsk, Ulyanovsk, Penza, Samara, Volgograd and Orenburg Regions. The same was observed on certain days in the Central Russia and in the south of the country. In the last days of the month, night frosts came to the Moscow Region. The anomalies of decade-averaged temperatures in the Urals and in West Siberia were -3…-5°. The air temperature was above normal in the west and the east of the country only, approximately by 3-7°.

As a result, the monthly-averaged temperature in April was just slightly higher than its normal value in most parts of the European territory, in the Urals and partly in Western Siberia, but was even lower than usual in some of these regions (foothills of the Northern Caucasus and parts of the Omsk, Novosibirsk and Tyumen Regions). At the same time, the anomalies of monthly averaged temperature in the east of the country reached +4…10°. The average April temperature in Russia entered the Top Ten of highest values in the meteorological chronicle. In the north of the Far East Federal district, this April was the warmest in the history. Eight out of ten warmest Aprils in this area belong to the XXI century.All over East and South Asia, the weather remained warm. In Mongolia and in the north of China, the monthly-averaged air temperatures exceeded the normal values by 3-5°. The highest monthly average first achieved in April 1998 was reproduced in China. In Indochina, the anomalies of +2…4° were observed. In Thailand, the air temperature reached +35°.In the north of India, the weather was hot. The air in the north-west of the country heated to +45° in expectation of the summer monsoon.In most parts of Central Asia, the temperatures in April were normal even though daily maxima were recorded in some areas (e.g., in Kyrgyzstan).In the Near and Middle East, it was cooler than usual. The air temperature in April was 1.0-1.5° below normal in some areas.In North Africa, the air temperature was generally normal everywhere excluding the central part in the region of Lake Chad where it exceeded the normal value by about 2°.In Europe, abnormally warm weather persisted. The monthly-averaged temperature was in the Top Ten of highest values recorded for the whole history of meteorological observations. The normal figures were exceeded by 2-3° or more in the east and the north of the continent (in Austria, Hungary, Czechia, Poland and Ukraine, in the Baltic and Scandinavian countries, in Belarus and Germany). New temperature maxima were reported in some countries.In the USA and Canada, the monthly-averaged air temperature was close to normal in central regions. On the West Coast, namely, in the regions bordering the Pacific, it was higher than that: by 2-4° or more in some areas of California and British Columbia. In the east, i.e., on the Atlantic Coast, it exceeded the normal value by about 2°. The temperature in the north of Canada and in Alaska was noticeably higher than normal.In the Arctic where global warming is more conspicuous than on the rest of the Globe, the monthly-averaged temperature was well above the normal value again – by 4° on the average – to occupy the 5th place in the ranking list compiled for the whole history of meteorological observations.The air temperature in April averaged over the entire Northern Hemisphere became the second highest one after the unrivalled value recorded in April 2016.In Moscow, the average temperature in April was +8.1°, with the anomaly of +2.3°.

Ocean Surface Temperature

A weak El Nino survived in the east equatorial latitudes of the Pacific Ocean. The mean anomaly of ocean surface temperature was less than +1° in the El Nino recording area (120-170°W and 5°N – 5°S); as for the whole part of the Pacific Ocean in the Northern Hemisphere, this anomaly was the same as in the previous month. As a precursor of El Nino termination in the near future, abnormally cold waters formed off the coasts of South and Central America. The ocean surface temperature above the normal value could be traced at the coasts of Alaska and Canada and in individual subtropical water areas, and below the normal value, in the Sea of Okhotsk and in the western tropics of the Ocean.As for the Atlantic Ocean, its mean surface temperature anomaly also remained the same as in the previous month. Large positive anomalies were observed in the subtropics in the west of the Ocean, in the Davis Strait, and in the Baltic, Northern and Barents Seas. Water was still colder than usual in tropical and central regions of middle latitudes.

Precipitation

This month was extraordinary dry in most parts of the European territory of Russia. In most constituent territories of the Central, North-West and Volga Federal districts, the monthly amounts of precipitation did not even reach 50% of their normal value, and were less than a tenth of that value in the Novgorod, Pskov and Kaliningrad Regions. Nothing similar in April has been observed in the Russian Plain for almost fifty years already. Spring snowfalls rather than rains would still occur to result in a temporary restoration of the snow cover already melted in March, e.g., in the Moscow Region and in Saint-Petersburg where its height reached 2-4 cm again.Cyclones carried moisture to the south of Russia only. Heavy rains fell in the Crimea, Krasnodar Territory, Rostov and Astrakhan Regions, and Northern Caucasus. The intensity of precipitation was sometimes higher than 30 mm per day. In certain areas of the Astrakhan Region, the normal monthly precipitation amounts were exceeded by 2 to 3 times.The precipitation was close to normal in the Urals but very abundant in some places to the east of them. The usual totals were exceeded by two or more times in certain regions of the Krasnoyarsk Territory, and by 1.5 or more times in the Tomsk Region and the Altai Territory on the average. Precipitation was often in the form of snow both in the north (which is quite habitually) and in the south of Siberia.The weather in the east of Russia, and in its west alike, turned out to be dry. The Amur and Magadan Regions and the north of the Khabarovsk Territory were the only exceptions with the monthly precipitation totals reaching their normal values; it was much drier everywhere else. In Yakutia, in the Magadan Region, in the Khabarovsk Territory and in Chukotka, snowy weather was still sending its reminders from time to time.In most parts of China excluding its north-eastern and north-western regions, the precipitation amounts were normal or increased. In the middle of the month, continuous showers caused the flood killing humans and under-flooding buildings in the province of Guangdong, while in the middle of the third decade, the eastern provinces of the country suffered from such showers. In neighbouring North Korea, the meteorological service reported the precipitation amount recorded since the beginning of 2019 was about 40% of the normal value: this could possibly cause a drought in the country.Dry weather prevailed in South-East Asia: heavy rains were observed in the northern Vietnam and in Indonesia only. In the latter case, they caused river floods and landslides. The traffic circulation was disrupted. The fatalities and the cases of victims' evacuation from the disaster areas were reported.In the central regions of India, rains were pouring even though the monsoon season had not started yet. The normal monthly precipitation amounts in some places were exceeded by two to three times. Yet, it was still dry in the rest of the country and in adjacent Pakistan.Rains continued tormenting Central Asia. The monthly precipitation amounts in Uzbekistan, Tajikistan and Afghanistan were two to three times larger than normal. These rains were very intensive. Thus, they brought 35 mm of atmospheric moisture for a single day in Dushanbe. Hundreds of people were killed by floods in Afghanistan. Tashkent was literally drowned. Many fields sown with cotton seeds were submerged in water. Many residents of villages in Turkmenistan temporarily moved to natural elevations formed by barchans. Such prolonged rains are extremely rare in this region.In neighbouring Iran, floods were rife as in March when there were a lot of them. Their outcome was normal in most parts of the country, or higher than normal in the northern regions bordering Turkmenistan. Rains spread over the Near East territory as well. The normal precipitation amounts were exceeded by two or more times all the way from Lebanon to Iraq. The situation was similar in the UAE. At the same time, the precipitation was very scarce in Saudi Arabia.In North Africa, most rains were observed along the Mediterranean coast.Considering how the precipitations were distributed, the north and the east of Europe could be called antipodes of its south and its west. The weather was dry in the first case, with just about a half of the normal precipitation amounts achieved in Scandinavian and Baltic countries, in Belarus, Ukraine, Czechia, Slovakia, Hungary and Poland. In the second case, these amounts were achieved in full, or exceeded by 1.5-2.5 times in certain areas of Spain, in the south of France, in Italy and in Greece. Venice was flooded by showers, and a new record for the height of water level in the St Mark's Square was established. Torrents in Athens, the capital of Greece, totally blocked traffic circulation, destroyed power transmission lines, washed out roads and under-flooded buildings. Five days of incessant rains in the island of Crete turned its motor roads into Venetian canals. And while the south of Europe was flooded with rains, its northern and mountainous areas were still targeted by snow: in the Alps, it added extra 70-90 cm to the height of snow cover in some places. In Switzerland, the snow thickness at one of the ski resorts was reported to exceed seven metres.In the USA, large amounts of precipitation were observed. Their monthly totals reached or often exceeded the normal value everywhere except in California. One and a half times this value was considered commonplace in this month, and the amounts exceeding it by two or three times were observed in the southern states of Texas and Louisiana or in the western states of Oregon and Washington. As for the north-west of the country, this April entered the Top Ten of "wettest" ones in the history of meteorological observations. In the Midwest, sustained rains caused a severe flood: water in the rivers rose close to record-breaking levels, and the fatalities were reported. In the northern state of Illinois, a snowstorm paralysing operation of the Chicago airport occurred in the north of the country.In the east of Canada, a powerful snowfall occurred in the beginning of April. In the provinces of New Brunswick and Nova Scotia, the normal monthly amount of precipitation was gained in a single day, creating snow banks. The snowfall was followed by freezing rain that resulted in an ice crust up to 4 cm in thickness causing numerous breaks of wires on power transmission lines and numerous road accidents in the south of Quebec. But the amounts of snow were even larger in the north of the country: they exceeded the normal values by 3-4 times in some places. The western provinces close to the Pacific Coast received little precipitation during this month.The amounts of precipitation were even smaller in Mexico, with zero figures recorded on the meteorological stations in most parts of the country. In Columbia, the season of showers was in place. These showers produced a massive landslide that descended onto the Pan-American Highway which is an important traffic artery connecting the north and south of the New World.The monthly precipitation in Moscow amounted to 9 mm only, i.e., to 20% of the normal value. In April 1970, almost 50 years ago, the quantity of atmospheric moisture in the capital was even lower, and in 1992, it was the same. As a result, this April is in the Top Ten of its driest cognate months for 129 years of instrumental weather observations on a regular basis.